The present application relates to a lateral heterojunction bipolar transistor (HBT) structure, and particularly to a lateral heterojunction bipolar transistor (HBT) including an epitaxial grown base and methods of manufacturing the same.
Heterojunction bipolar transistors (HBTs) include a heterojunction, i.e., a junction of two semiconductor materials having different band gaps, which coincide with a p-n junction between the base and the emitter. The wider band gap of the emitter relative to the band gap of the base in an HBT increases the current gain relative to a bipolar junction transistor employing a same semiconductor material across the base and the emitter and having similar physical dimensions and doping profiles for the base and emitter.
However, there can be difficulties associated with the manufacturing of the HBTs and with the functioning of HBTs. For instance, in the conventional art, the base is formed first which, in turn, may require additional patterning (e.g., lithography and reactive ion etching (RIE)) in order to enable deposition or epitaxial growth of the emitter/collector material to form an HBT having an emitter/collector including materials with a wider band gap than that for an intrinsic base, thereby resulting in a more complicated process for forming the HBT. Moreover, an HBT produced in the conventional art may also fail to provide sufficient isolation between the emitter and the extrinsic base and the collector and the extrinsic base.